1. Technical Field
The present invention relates to a semiconductor integrated circuit, and more particularly, to an apparatus for controlling a voltage in the semiconductor integrated circuit.
2. Related Art
As the integration of semiconductor memory apparatuses increases, a separate voltage is used in a core region to reduce power consumption or an elevated voltage for performing an overdriving operation is used to access data at a high speed. In recent years, internal voltages having various voltage levels have been generated and used in the semiconductor memory apparatus. In order to generate internal voltages having varied voltage levels, a semiconductor memory apparatus includes a reference voltage generating circuit that supplies a reference voltage VREF.
In general, a reference voltage generating circuit or an internal voltage generating circuit includes a switch that transmits a generated voltage to a predetermined portion in the semiconductor memory apparatus. This switch may be a PMOS transistor. However, in a general PMOS transistor, when a temperature is decreased, a threshold voltage Vth is increased. For this reason, the current supply capability of the PMOS transistor that operates with the switch is lowered, and thus a level of a reference voltage (or an internal voltage) is changed. As a result, it is difficult to secure the reference voltage (or the internal voltage) accurately due to the variation in the reference voltage or (the internal voltage). Furthermore, in order not to use the switch composed of the PMOS transistor, a new reference voltage generating circuit or internal voltage generating circuit needs to be designed, which causes not only inconvenience but also an increase in manufacturing costs due to a new circuit design.